Boris Johnson will only be ousted from No 10 if the Liberal Democrats take seats from the Tories at the next general election, party leader Sir Ed Davey will say.
In his keynote address to the annual Lib Dem conference on Sunday, Sir Ed will urge activists to take on the Conservatives in their traditional heartlands and “crush the Tory blue wall”.
Following the party’s stunning victory in the Chesham and Amersham by-election – where they overturned a 16,000 Tory majority to win by more than 8,000 votes – he will say they now hold the key to the next general election.
“Make no mistake, the electoral arithmetic is clear. These Conservatives can’t be defeated next time unless we Liberal Democrats win Tory seats,” he will say, according to advance extracts of his speech. .
“Boris Johnson will stay in Downing Street unless we throw him out.
“It’s why our victory in Chesham and Amersham was so important. We showed, against all the odds, that even in deepest, bluest Buckinghamshire the Tories can be beaten.
“And we showed Liberal Democrats are the ones to do it.”
Sir Ed’s address will mark his first speech to a live audience since becoming party leader last year.
He will speak to a small audience of about 100 of the Lib Dem faithful at London’s Canary Wharf – although the majority of the conference is still being held online due to the pandemic.
The speech will include a clear pitch to “soft” Tory voters, with promises to champion small businesses and protect those who “play by the rules”.
“If you do your bit, if you play by the rules, you should be able to afford a decent home in a safe, clean neighbourhood – with a comfortable retirement when the time comes,” he is expected to say.
“Your children should be able to go to a good school, get a good job, and have real opportunities to fulfil their potential.
“You should be able to know that if anyone in your family is ill, frail or disabled, they will get the high-quality health and social care they need.”
Sir Ed will promise a “radical fair deal” for small businesses, saying the case for supporting them was “overwhelming”.
“These are the businesses and people creating the most jobs,” he is expected to say.
“These are the businesses and people who are so fundamental to our local economies, our communities and our high streets. Of course Liberal Democrats are their champions.”
Ahead of the Cop26 international climate change summit in Glasgow, he will also call for a ban on new oil, coal and gas companies listing on the London Stock Exchange.
“The UK should be leading the world on climate action, with a radical new approach,” he is expected to say.
“To move trillions of dollars, yen, euros and pounds out of fossil fuels and into renewables by properly holding to account the powerful fossil fuel firms and the powerful in the City of London.
“As we host the global climate talks in Glasgow, we should stop London hosting the world’s fossil fuel investments.”